1. Field of the Invention
The present invention relates to potting materials and media based on polyurethanes produced with castor oil, to a process for their preparation as well as to their use.
2. Brief Description of the Background of the Invention Including Prior Art
Potting relates to a process in which a material, or an assembly of small discrete units, is coated with, or imbedded in, a molten film, sheath or foam usually of an elastomer such as a polyurethane. A foam forming plastic such as polyurethane may be used to fill the spaces between various components so that they are imbedded in and supported by the foam. Plastics such as polyurethanes used for this purpose are often called potting compounds.
In microencapsulation a material is enclosed in capsules ranging from 20 to 150 micrometers in diameter, which are composed of polymeric substances such as polyurethanes.
A polyurethane is a thermoplastic polymer, which can be made polysetting, produced by the condensation reaction of a polyisocyanate and a hydroxyl containing material for example a polyol derived from propyleneoxide. The basic polymer unit is formed as follows: R.sub.1 NCO+R.sub.2 OH.fwdarw.R.sub.1 NHCOOR.sub.2. Polyurethane elastomers show good resistance to abrasion, weathering and organic solvents, they tend to harden and to become brittle at low temperatures and they are combustible.